Perforated Concrete Pipes

Marshalls CPM manufactures precast concrete perforated pipes up to 600mm diameter that transport and distribute storm water into the rock filled trench and eventually into the surrounding area through the circular perforations.

Concrete perforated pipes are suitable for field drains or french drains.

Perforated pipes are no longer a British Standard product. The pipes are drilled whilst wet and the semi-dry nature of the concrete used in the manufacturing process leads to spalling on the inner and outer surfaces around the holes. This is cosmetic only and does not affect the integrity of the pipes for land drainage use.

Perforated pipes comply with the Department of Transport Specification for Highway Works, which states the total area of drainage holes should not be less than 1000mm2 per metre length of pipe.

If you require a larger diameter than 600mm please contact our specials team who may be able to help

For sales into England and Wales please call 01179 814500 or email sales@cpm-group.com

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Are there any precautions to take for concrete pipes laid to steep gradients?

It is recommended that anchor blocks be cast into the ground every 3 or 4 pipe joints behind the socket (also consider installing packers on the face of sockets to prevent concrete to concrete contact).

How frequent should I be testing the pipeline during installation?

It is highly recommended to test the pipeline every 3 or 4 pipes laid as an absolute minimum (do not wait until whole line is installed before carrying out such test).

What are the appropriate ‘roughness values’ for concrete pipes?

Roughness values are:

Foul sewers: 1.5mm.

Surface water sewers: 0.6mm.

What are the recommended minimum depths of cover for concrete pipes?

Minimum depth of cover to top of pipes is 0.6m with bedding class S (360o granular bedding). For cover depths less than 0.6m, then the pipeline should be protected with either a full concrete surround, or a reinforced concrete slab should be placed over it (spanning sufficient distance onto trench walls).

What concrete pipes are generally reinforced?

Marshalls CPM concrete pipes are generally reinforced in sizes DN675 and above (it is possible to reinforce some of the smaller sizes and also to provide un-reinforced pipes in some of the larger sizes – usually made to order).

What is the maximum permissible velocity in concrete pipes?

Limits are not normally placed on maximum velocities but certain criteria such as the potential for erosion should be considered for steep gradients.

What is the maximum working pressure that concrete pipes can withstand?

Concrete pipes are designed to operate at low heads of water. The BS performance requirement is set at a minimum of 0.5 bar.

What is the most likely cause of air test failure for a concrete pipeline on site?

Common causes of air tests failures include:

Displaced seals (usually due to use of wrong pipe lubrication during installation).

Poor laying technique.

Faulty testing equipment.

Poor seal between testing equipment and face of concrete pipe.

What materials can be used as backfill for a concrete pipeline?

In many situations the ‘as-dug’ trench material is suitable for backfill (should be readily compactable and free from large boulders etc).

What sizes of concrete pipes are subject to testing when installed?

It is common practise to carry out air or water testing of pipes normally up to DN750 and a visual inspection above this size.

What strength of concrete pipes is available?

Circular concrete pipes are all manufactured to strength class 120 (minimum crushing load for a particular size of pipe is equal to 120 multiplied by DN of pipe divided by 1000).

What typical joint gaps should be achieved when jointing concrete pipelines?

Joint gaps between pipes should be measured on the internal surface and should ideally be between 5-25mm.